Leaf Nitrogen Levels Research Articles

Effect of post-silking drought stress on the expression profiles of genes involved in carbon and nitrogen metabolism during leaf senescence in maize (Zea mays L.)

Drought stress during reproductive growth stages greatly affects the growth and productivity of maize plants. To better understand the metabolic regulation during post-silking drought (PD) stress, an RNA sequencing (RNA-Seq) analysis was performed at the late stage of leaf senescence in maize. Physiological measurements showed that PD stress reduced both leaf carbon and nitrogen levels. A total of 4013 differentially expressed genes (DEGs) were found based on RNA-Seq analysis, 115 of which were identified to be involved in photosynthesis and in the metabolism of sucrose, starch, and amino acids. Among these DEGs, 14 genes involved in photosynthesis were down-regulated. The genes coding for sucrose and pectin synthesis were up-regulated under PD stress. The two genes of asparagine synthetase (ZmAS3 and ZmAS4), which are responsible for nitrogen remobilization in leaves, were also significantly induced by the drought treatment. The expression profiles of these genes involved in carbon and nitrogen metabolism suggests their regulatory roles during drought-induced leaf senescence.

The Effects of Silica Fertilizer as an Anti-Herbivore Defense in Cucumber

Abstract This study aims to improve our understanding of silicon’s role in deterring herbivores from Cucumis sativa. We hypothesized that silicon’s role in plant defense is due to the presence of silica augmenting other physical and/or chemical defenses used by the plant. Using C. sativa plants treated with either a silica fertilizer treatment (Si+) or a control solution (Si-), we monitored feeding preferences of two types of herbivores, a chewing herbivore (Diabrotica balteata) and a piercing/sucking herbivore (Bemisia tabaci). Leaves from treatment plants were visited less and eaten less than leaves from control plants. We then assessed the differences in physical defenses by comparing the leaf structural components, nutrient and water content, and trichome density between treatment and control plants. For chemical plant defenses, we measured leaf carbon and nitrogen levels in, and volatile organic compounds (VOCs) from treatment and control plants. We found no significant difference between treatment and control plants in: lignin content, most elemental plant nutrients, water content, trichome density, and quantity of carbon and nitrogen. We did see an increase in the VOC Indole, known for plant defense priming, an increase in phosphorous levels and a decrease in cellulose levels in silica treated plants.

The effects of forage removal on biomass and grain yield of intermediate and spring triticales

The dual-purpose use of cereals can be a convenient management option if grain yield (GY) is not significantly reduced. The effects of clipping at the terminal spikelet stage on biomass and grain production of an intermediate (‘Bienvenu’) and a spring (‘Oceania’) triticale cultivar grown at two sowing rates (300 and 600seedsperm2) were analysed in terms of the changes induced on radiation and water capture and use and biomass partitioning in five different Mediterranean environments with no additional N application following clipping. Clipped crops were able to recover completely in terms of the fraction of radiation interception (FIPAR) before anthesis, but the period in which plants exhibited a smaller leaf area resulted in a severe reduction − from 20 to 26% depending on the environment- in the total amount of radiation intercepted (IPAR, MJm−2), and consequently, in biomass at anthesis (from 14 to 30%). Radiation use efficiency (RUE) between clipping and anthesis ranged from 0.89 to 1.42gMJ−1, and only contributed to the decrease in biomass when leaf nitrogen levels were reduced as a consequence of clipping. Evaporation increased (by 13mm on average) and transpiration decreased (by 11mm on average) following clipping, with contrasting but quantitatively small effects on evapotranspiration. Transpiration efficiency decreased by about 20% following clipping in most environments because clipping decreased biomass production more than evapotranspiration in environments that did not allow the triticale crops to reach leaf area index values greater than 3–4. GY varied from about 300 to 850gm−2 and was only affected by clipping in the two environments with favourable post-anthesis conditions where unclipped crops showed a higher harvest index (HI, 0.38 unclipped vs 0.36 clipped crops on the average of the two environments). In the environments where a severe water stress (transpiration lower than 18% of reference evapotranspiration) following anthesis led to similar amounts of IPAR under the two treatment conditions, the lower biomass at anthesis of clipped crops lead to a higher HI and no reduction in GY. No interaction between clipping and cultivar was observed for FIPAR. Cultivar differences derived from their different phenologies and were mainly expressed before clipping; the longer duration of the phase prior to clipping (from 0 to 18days depending on the environment) resulted in the intermediate cultivar being superior in terms of winter forage production (193 vs 135gm−2 on average). On the other hand, the intermediate cultivar was less advantageous in terms of GY (270 vs 357gm−2) in the environments presenting the most severe terminal water stress. Sowing rate was only relevant in the pre-clipping period when the higher sowing rate produced, on average, 40% more biomass than the lower sowing density. Dual-purpose triticale can be a convenient management option in Mediterranean environments subjected to severe terminal water stress because GY is not affected and a variable amount of winter forage may be obtained.

The Effects of Fall Urea Sprays on the Leaf Size and Nitrogen Level of Spur Leaves in Sweet Cherry (Prunus avium)

Bu calismada 0900 Ziraat cesidi kiraz agaclarina sonbahar ortasinda yedi gun aralikla iki kez puskurtulen dusuk biuretli urenin spur (mayis buketi) yapraklarinin buyuklugune ve azot icerigine olan etkisi incelenmistir. Denemede uygulama olarak agac basina 32.5 g ve 62.5 g olmak uzere iki ure dozu puskurtulmus olup ayrica tanik agaclar da yer almistir Spur ve surgun yapraklarinin iriligi sonbahar ure uygulamasindan olumlu etkilenerek tanik agaclarinkine gore en az iki kat daha fazla olmustur. Ure uygulamasi ilkbaharda spur yapraklarin N icerigini de arttirmistir. Sonbaharda yapraktan dusuk biuretli ure uygulamasinin 0900 Ziraat cesidi kiraz agaclarinin spur yapraklarinin iriliginde artis sagladigi ve boylece meyvelerin de iriligine olumlu etki saglayabilecek etkili bir uygulama oldugu anlasilmistir

Low Incident Light Combined with Partial Waterlogging Impairs Photosynthesis and Imposes a Yield Penalty in Cotton

AbstractThrough field studies, cotton responses to dual stresses – waterlogging and low light (shade) were investigated. The hypothesis was that shade would amplify yield losses in waterlogged (WL) cotton. Either early or late in the reproductive phase, the crop was WL (96 h and 120 h, in 2012–2013 and 2013–2014, respectively) and/or shaded (6 days or 9 days in 2012–2013 and 2013–2014, respectively). Waterlogging at early reproductive phase significantly reduced lint yield (17 % averaged across both years) of cotton, although shade‐induced yield losses (18 %) were only significant in 2013–2014. Shade significantly exacerbated yield losses only when the impact of waterlogging damage was modest (2013–2014). More intense waterlogging impaired lint yield independently of the light levels. Yield reductions in these experiments were the consequence of both accelerated fruit abscission and fewer fruiting nodes produced. Plants had lower leaf nitrogen levels and photosynthetic rates after waterlogging and/or shade treatments and produced fewer fruiting nodes. Although long‐term shade increased specific leaf area (30 %) and leaf N (20 %) immediately following 5 days of waterlogging, it did not restore shoot growth, node formation or lint yield because of suppressed photosynthetic performance (area basis) and carbohydrate supply.

Key minerals influencing apple quality in Chinese orchard identified by nutritional diagnosis of leaf and soil analysis

We investigated the correlation between leaf/soil minerals and fruit quality in apple trees grown in orchards, with the ultimate goal of improving the latter. Leaf mineral nutrients; soil nutrients in the 0–20, 20–40, and 40–60 cm layers; and fruit quality traits in 32 apple orchards in China were monitored for 2 years. Significant factors associated with fruit quality were identified via correlation analysis. An analysis of leaf data revealed that leaf nitrogen (N) and leaf magnesium (Mg) levels were extremely high in 75 and 89% of the orchards, respectively. In the Bohai Gulf region, 94% of the orchards showed significantly higher values than the standard. The soil pH values of the orchards in eastern China like eastern Shandong or Liaoning were lower than 7.0, while the pH values in the Loess Plateau of northwestern China like Shaanxi were much higher than 7. Soil alkali-hydrolyzable N levels in 47% of the orchards were lower than the optimal level of 70 mg kg−1. Generally, the soil alkali-hydrolyzable N levels of orchards in the Bohai Gulf region were significantly higher than those in the Loess Plateau region. The available P levels in the orchards of the Bohai Gulf region were up to three times higher than those of the Loess Plateau region. However, although the available potassium (K) in most orchards was sufficient (51.39–309.94 mg kg−1), leaf K content in 73% of the orchards was low, possibly due to fruit bagging or fruit overload. Approximately 63% of the orchards in Shandong and 29% of the orchards in Shannxi showed leaf Fe deficiencies. In the Loess Plateau, most orchards showed high leaf Ca levels, a strong correlation was observed between leaf and soil phosphorus/potassium (P/K) content and fruit organic acid content. The amounts of fruit soluble sugar or fructose were positively correlated with soil calcium/potassium (Ca/K) levels and leaf calcium/boron (Ca/B) levels in most orchards. The excessive leaf N levels caused by the extensive application of N fertilizers had a negative effect on fruit quality in most apple orchards in China. P, K, Ca, and B were key minerals associated with fruit quality.

Application of fluorescence spectrum to precisely inverse paddy rice nitrogen content

Paddy rice is important for Chinese agriculture and crop production, which largely depends on the leaf nitrogen (N) levels. The purpose of this study is to discuss the relationship between the fluorescence parameters and leaf N content of paddy rice and to test their performance in inversing N content of crops through back-propagation (B-P) neural network. In the correlative analysis of the fluorescence parameters and the N content, we found that the correlation between fluorescence ratios (F740/F685 and F685/F525 (F740, F685, F525 - intensity of fluorescence at 740, 685 and 525 nm, respectively)) and the N content (R-2 are 0.735 and 0.4342, respectively) is weaker than that between the intensity of fluorescence peaks (F685 and F740) and N content (R-2 are 0.9743 and 0.9686, respectively). Our studies show that the accuracy and precision of N content inversion which is acquired from the intensity of fluorescence peaks through the B-P neural network model are significantly improved (root mean square error (MSRE) = 0.1702, the residual changes between -0.1-0.1 mg/g) compared with the fluorescence ratio (MSRE = 0.3655, the residual changes from -0.3-0.3 mg/g). Results demonstrate that the intensity of fluorescence peaks can be as a characteristic parameter to estimate N content of crops leaf. The B-P neural network model will be serviceable approach in inversing N content of paddy leaf.

Critical ranges for leaf nitrogen and potassium levels in coffee fertigated at the production phase1

With the aim of establishing critical ranges for the leaf nitrogen (N) and potassium (K) levels in fertigated coffee crops under production, an experiment was carried out in the experimental area of the Sector for Coffee Cultivation of the Department of Agriculture at the Federal University of Lavras, in Brazil. Treatments consisted of five levels of fertilizer applied through fertigation: 30%, 80%, 130%, 180% and 230% of the recommended amounts of N and K for rainfed coffee grown in Minas Gerais. A randomised block design with four replications was used. Critical ranges for nutrient concentrations in the leaves were established from the results of growth characteristics (plant height and stem diameter), leaf analyses and productivity. The results obtained were: a) nitrogen (g kg-1): 32.39 to 32.40 for January/February; 33.60 to 33.61 for March/April; 27.39 to 27.42 for May/June; 24.23 to 24.24 for July/August; 26.06 to 26.09 for September/October and 26.50 to 26.51 for November/December; b ) potassium (g kg-1): 20.08 to 20.14 for January/February; 17.89 to 17.91 for March/April; 15.93 to 15.96 for May/June; 15.29 to 15.35 for July/August; 16.61 to 16.64 for September/October and 20.58 to 20.64 for November/December.

Physiological Character of Cocoa Clones that Cultivated under Three Species of Shade Trees

This experiment aims to know the solar energy efficiency of four clones of cocoa that cultivated under three different shading plants. This experiment has been done from September until December 2013 located at Kaliwining Experiment Farm with characteristic 45 m above sea level, soil type is low humic gley, soil texture is silty clay loam, and climate classification type D based on Scmidht and Fergusson classification. This experiment used nested design as experimental design with species of shading plant as main plot which are teak (Tectona grandis L.), krete (Cassia surattensis (Burm.) F.), lamtoro (Leucaena leucocephala L.) and cocoa clones as sub plot which are Sulawesi 1, Sulawesi 2, KKM 22, and KW 165. The observation of physiological character consists of the level of leaf chlorophyll, the level of leaf nitrogen, spesific leaf area, leaf area index, the amount of stomata, and stomatal density. The experimental result showed that there is differences (heterogenity) between shading location based on homogenity test by Bartlett method. The interaction effect between plant spesies and cocoa clones are affect the leaf area index and stomatal density, whereas the level of leaf chlorophyll, the level of leaf nitrogen, and spesific leaf area was affected by the kind of plant spesies. Keywords : Physiological character, cocoa Ccones, shading trees, nested design, Bartlett method

Seed quality, chlorophyll content index and leaf nitrogen levels in maize inoculated withAzospirillum brasilense

The aim of this study was to evaluate differences between maize genotypes in relation to the germination response of the seeds and the growth of seedlings inoculated with Azospirillum brasilense, as well as the effect of inoculation on nitrogen levels and the chlorophyll content index of the leaves. The physiological seeds quality from the single-cross hybrids AG7098 and 2B707, and from the experimental synthetic varieties V2 and V4, inoculated with A. brasilense, was tested for germination, percentage and rate of emergence, and dry matter weight of the shoots and roots. Nitrogen levels and chlorophyll content index were evaluated in leaves of the same four genotypes grown in a greenhouse under different nitrogen supply systems and methods of inoculation with A. brasilense. The genotypes differ with regard to inoculation with A. brasilense. The hybrids were responsive to inoculation with A. brasilense for root dry matter weight. The V2 variety had a lower performance as regards root dry matter weight, with the opposite being seen for the dry matter weight of the shoots. V4 displayed no significant differences when inoculated. The results of the chlorophyll content index were not significant. Each genotype under evaluation displayed a different response for leaf nitrogen levels. It is possible to infer that the hybrids responded better to inoculation with the bacteria, with the greater root development leading to a better utilisation of water and nutrients.

Effect of girdling on leaf nutrient levels in pear cultivars Patharnakh and Punjab Beauty

The response of hard and semi-soft pear cultivars Patharnakh and Punjab Beauty, respectively to girdling was evaluated on 18-year-old vigorous plants growing under uniform cultural practices. Girdling was practiced on trunk (TG), limb (LG) and sub-limb (SLG) during flower initiation (FI), 15 days after flower initiation (15 DAFI) and 30 days after flower initiation (30 DAFI). Foliar leaf nitrogen and potassium levels in both the cultivars were significantly reduced with girdling treatments. However, foliar calcium level was significantly enhanced up to 3.93% in Patharnakh and 3.62% in Punjab Beauty, whereas, phosphorus and magnesium levels were not significantly influenced with girdling in both the cultivars. Among micro-nutrients; iron, zinc and copper contents were recorded significantly higher in girdled trees, however, manganese content was reduced significantly in both the cultivars.

Genetic variation in the critical specific leaf nitrogen maximising yield among modern maize hybrids

A major aim in breeding programs is to improve nitrogen use efficiency (NUE). The critical level of specific leaf nitrogen (SLNc) maximising growth and yield is a relevant trait influencing NUE. The relationship between growth or yield and SLN is hyperbolic indicating that levels of SLN higher than the critical would tend to decrease NUE. It has been recently proposed that maize breeding may profit of this relationship by phenotyping SLN and selecting for genotypes with SLN=SLNc (SLN<SLNc would result in low yields, SLN>SLNc would bring about high yields but at the expense of low NUE); being the SLNc=1.5gNm−2. For this proposal to be realistic, genotypic variation in SLNc should be negligible. We aimed to determine the degree of genetic variation in SLNc in a range of modern maize hybrids. For this purpose, we carried out four field experiments with 11 contrasting maize hybrids grown under fertilized (200kgNha−1) or unfertilized conditions in each of the four experiments. At silking, leaf area and N concentration of leaves were determined and at maturity, yield and biomass were measured. Analysing the whole dataset together (n=88) we found a very large range of all variables measured and calculated: yield varied between c. 6 and c. 18Mgha−1 and SLN from c. 0.7 to c. slightly more than 2.5gNm−2. Within that context we found a significant bi-linear regression between yield and SLN (p<0.001). Analyzing each hybrid individually we did find substantial variation among hybrids in SLNc, ranging between c.1.0 and c.s1.93gNm−2. The variation was also substantial calculating SLNc with an alternative methodology and if leaf N content instead of SLN were used as independent variable. Genotypic differences in SLNc were positively related to N uptake but unrelated to other traits for which hybrids varied, including yield potential. Additionally, genotypes with low SLNc show a tendency for a better NUtE. We concluded that it does not seem appropriate to phenotype for a particular value of SLNc as any particular threshold might bring about selected lines with either a yield potential lower than possible and/or with a relatively lower than possible NUE.

Competitive Effects of Hybrid Corn (Zea mays) on Replanted Corn

Initial corn (IC) in a replant situation, which is surviving corn from the initial planting, as well as volunteer corn from the previous season, is a competitive weed, but little is known regarding the effect of IC density on grain yield of desirable replant corn (RC). Field trials were established in central and northeast Missouri during 2008 to 2010 to determine the impact of IC on the leaf chlorophyll, stalk diameter, and grain yield of RC. Glyphosate-resistant RC was planted in 76-cm rows, with hybrid glyphosate-resistant IC established for season-long competition between rows at densities of 0 to 8 plants m−2. At vegetative growth stages with six and eight leaf collars and at tasseling (V6, V8, VT), RC leaf nitrogen levels were reduced by 5 to 30% in the presence of IC at densities of one to eight plants m−2compared with control plants lacking competition. Stalk diameters of RC at the VT growth stage were reduced from 8 to 30% by IC as densities increased from 0.5 to 8 plants m−2. Grain yield of row corn was reduced by IC, with yield losses ranging from 7 to 81%. Growth rate and biomass accumulation of hybrid and volunteer corn from V2 to VT were compared in the greenhouse to determine if competitive potential was similar. The second filial generation (F2) of corn from hybrid (DKC ‘63-42′) corn was collected from a field in central Missouri and southeastern Nebraska. There were no statistical differences found in growth rate or biomass accumulation between hybrid and F2corn up to VT, although F2plant biomass was numerically (up to 41%) lower at numerous growth stages. Hybrid corn is likely to be equally or more competitive with RC than volunteer corn. This research documents that in areas where IC remains among replanted corn, the IC has a negative impact at all densities evaluated.

Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

Quantitative, spatially explicit estimates of canopy nitrogen are essential for understanding the structure and function of natural and managed ecosystems. Methods for extracting nitrogen estimates via hyperspectral remote sensing have been an active area of research. Much of this research has been conducted either in the laboratory, or in relatively uniform canopies such as crops. Efforts to assess the feasibility of the use of hyperspectral analysis in heterogeneous canopies with diverse plant species and canopy structures have been less extensive. In this study, we use in situ and aircraft hyperspectral data to assess several empirical methods for extracting canopy nitrogen from a tallgrass prairie with varying fire and grazing treatments. The remote sensing data were collected four times between May and September in 2011, and were then coupled with the field-measured leaf nitrogen levels for empirical modeling of canopy nitrogen content based on first derivatives, continuum-removed reflectance and ratio-based indices in the 562–600 nm range. Results indicated that the best-performing model type varied between in situ and aircraft data in different months. However, models from the pooled samples over the growing season with acceptable accuracy suggested that these methods are robust with respect to canopy heterogeneity across spatial and temporal scales.

Do the rich always become richer? Characterizing the leaf physiological response of the high-yielding rice cultivar Takanari to free-air CO2 enrichment.

The development of crops which are well suited to growth under future environmental conditions such as higher atmospheric CO2 concentrations ([CO2]) is essential to meeting the challenge of ensuring food security in the face of the growing human population and changing climate. A high-yielding indica rice variety (Oryza sativa L. cv. Takanari) has been recently identified as a potential candidate for such breeding, due to its high productivity in present [CO2]. To test if it could further increase its productivity under elevated [CO2] (eCO2), Takanari was grown in the paddy field under season-long free-air CO2 enrichment (FACE, approximately 200 µmol mol−1 above ambient [CO2]) and its leaf physiology was compared with the representative japonica variety ‘Koshihikari’. Takanari showed consistently higher midday photosynthesis and stomatal conductance than Koshihikari under both ambient and FACE growth conditions over 2 years. Maximum ribulose-1,5-bisphosphate carboxylation and electron transport rates were higher for Takanari at the mid-grain filling stage in both years. Mesophyll conductance was higher in Takanari than in Koshihikari at the late grain-filling stage. In contrast to Koshihikari, Takanari grown under FACE conditions showed no decrease in total leaf nitrogen on an area basis relative to ambient-grown plants. Chl content was higher in Takanari than in Koshihikari at the same leaf nitrogen level. These results indicate that Takanari maintains its superiority over Koshihikari in regards to its leaf-level productivity when grown in elevated [CO2] and it may be a valuable resource for rice breeding programs which seek to increase crop productivity under current and future [CO2].

Photosynthesis-nitrogen relationships in tropical forest tree species as affected by soil phosphorus availability: a controlled environment study.

Tropical soils are often characterised by low phosphorus availability and tropical forest trees typically exhibit lower area-based rates of photosynthesis (Aa) for a given area-based leaf nitrogen concentration ([N]a) compared with plants growing in higher-latitude, N-limited ecosystems. Nevertheless, to date, very few studies have assessed the effects of P deprivation per se on Aa⟷[N]a relationships in tropical trees. Our study investigated the effect of reduced soil P availability on light-saturated Aa and related leaf traits of seven Australian tropical tree species. We addressed the following questions: (1) Do contrasting species exhibit inherent differences in nutrient partitioning and morphology? (2) Does P deprivation lead to a change in the nature of the Aa⟷[N]a relationship? (3) Does P deprivation lead to an alteration in leaf nitrogen levels or N allocation within the leaf? Applying a mixed effects model, we found that for these Australian tropical tree species, removal of P from the nutrient solution decreased area-based photosynthetic capacity (Amax,a) by 18% and reduced the slope of the Amax,a⟷[N]a relationship and differences among species accounted for around 30% of response variation. Despite greater N allocation to chlorophyll, photosynthetic N use efficiency was significantly reduced in low-P plants. Collectively, our results support the view that low soil P availability can alter photosynthesis-nitrogen relationships in tropical trees.

Time of the season: the effect of host photoperiodism on diapause induction in an insect herbivore, Leptinotarsa decemlineata

Diapause, seasonal physiological dormancy, is the primary life history strategy used by insect species inhabiting temperate climates for seasonal synchronisation. Biotic signals for diapause induction originating from host plants may provide dependable cues for insects expanding from subtropical regions. We investigated the effect of plant‐mediated photoperiod cues on diapause initiation within the Colorado potato beetle, Leptinotarsa decemlineata Say. The effect of photoperiod changes on potato leaf composition and its subsequent correlation with diapause initiation was tested. Analyses revealed a significant effect of short‐day (LD 8 : 16 h and LD 10 : 14 h) photoperiod growth regimens on both nitrogen content in potato leaves and diapause initiation within L. decemlineata. Potato plants grown under short day conditions displayed significantly higher levels of leaf nitrogen compared with long‐day treated plants. Over 65% of beetles feeding upon short‐day treated plants initiated diapause compared with &lt; 20% of beetles placed upon long‐day treated plants. The observation of seasonality‐induced diapause signals by host plants signifies an important addition to the current array of plant–insect interactions. The present results suggest that seasonal synchrony may be the result of a more integrated system whereby host plant photoperiodism acts as an intermediate or supplementary physiological cue for diapause initiation.

Effects of soil surface management practices on soil and tree parameters in a ‘Cripps Pink’/M7 apple orchard 1. Mineral nutrition

Effects on soil, leaf and fruit element concentrations of organic (compost, straw mulch and hand weeding) and integrated (inorganic fertilisers and herbicide usage; IP) soil surface management practices in the tree rows, in combination with weed covers, cover crops and straw mulch in the work rows, were investigated in a seven-year trial. The trial took place on a gravelly soil in a ‘Cripps Pink’/M7 apple orchard in the Elgin area, South Africa. The organic treatments promoted higher phosphorus (P) and potassium (K) concentrations in the soil, leaves and fruit than the IP treatments. Leaf and fruit nitrogen (N) levels were normal in both the organic and IP treatments. Compost application rates that supply adequate N therefore deliver excessive amounts of P and K. Use of such composts should be based on P and K contents, supplementing where necessary with N. In both the IP and organic treatments, element concentrations were higher in the tree rows than the work rows. Treatments applied to the work rows did not affect soil and tissue element concentrations consistently. Standardisation of compost composition is required, as is balanced delivery of N, P and K.

Discrimination of the Lettuce Leaf Nitrogen Level Based on the BP Neural Network and the Spectral Information

According to the problem that the intelligence is not high of the soccer robot, using the mechanical theory as a guide, making some mechanical analyses and calculations on the pressure and transmutation states of chip kick mechanics, and conducting optimal design too, then making the structure of chip kick mechanics more and more rationalization. Experiments show that the new soccer robot controller features a quick response and high servo rigidity, and provide a kind of method for improving and perfecting the soccer robot control system, at the same time, filling the needs of producing.

Comparison of medium-term organic and inorganic fertiliser application on leaf nutrient concentration and yield of maize in rural agriculture in the Mbizana area, Eastern Cape province, South Africa

A five-year study was conducted in the Mbizana area, Eastern Cape province, to assess the seasonal and medium term effects of chicken manure and inorganic fertiliser application to an acid clay loam topsoil on nutrient element uptake and yield of maize in a field trial under dryland. Treatments consisted of a once-off application of three levels of dolomitic lime, annual application of two levels of inorganic fertiliser, and three levels of chicken manure. A no-till practice with hand planting and fertiliser application was used. Leaf and soil sampling, as well as harvesting were performed and analyses done. Chicken manure application induced similar maize leaf macro- and micro-nutrient concentrations to the recommended inorganic fertiliser (Frec) level and, in general, significantly higher values than the traditional fertiliser level (Ftrad). Augmenting chicken manure with inorganic nitrogen led to significant increases in leaf nitrogen and phosphorus levels. Grain yields under chicken manure were similar to those under Frec, but far superior to those under Ftrad. It is concluded that under acid soil conditions the improvement of soil fertility, either by organic or inorganic fertiliser application, can result in maize grain yields of about 3 Mg ha-1 under the prevailing rainfall conditions.